Enhanced 3d volumetric display

ABSTRACT

A three-dimensional volumetric display includes a light source that generates a two-dimensional image output and a transparent scattering volume, coupled to the light source on a first face of the scattering volume, that scatters the image output of the light source in a direction perpendicular to the light axis of the output of the light source; where the scattering volume comprises a three-dimensional array of scattering elements arranged in a plurality of scattering planes tilted relative to the first face of the scattering volume.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application Ser.No. 62/218,861, filed on 15 Sep. 2015, which is incorporated in itsentirety by this reference.

This application claims the benefit of U.S. Provisional Application Ser.No. 62/296,283, filed on 17 Feb. 2016, which is incorporated in itsentirety by this reference.

This application claims the benefit of U.S. Provisional Application Ser.No. 62/312,407, filed on 23 Mar. 2016, which is incorporated in itsentirety by this reference.

This application claims the benefit of U.S. Provisional Application Ser.No. 62/312,411, filed on 23 Mar. 2016, which is incorporated in itsentirety by this reference.

TECHNICAL FIELD

This invention relates generally to the image display field, and morespecifically to new and useful volumetric displays in the image displayfield.

BACKGROUND

Image displays are an integral part of modern life. From televisions tomonitors to smartphone and tablet screens, image displays provide userswith the ability to view and interact with information presented in avariety of forms.

Developments in the image display field have enabled displays to providea three-dimensional image viewing experience. Allowing users to viewimages in 3D results in a higher degree of realism in viewing as well asthe opportunity to perceive additional information over a similar imagedisplayed in two-dimensions.

Unfortunately, typical 3D displays (e.g., 3D TVs) are limited by theperspective they present to users; typically, all users of such displaysare forced to see a 3D scene through the same perspective unlessmultiple displays are present. Further, typical 3D displays oftenrequire the use of glasses.

Volumetric displays enable multiple users to view the same 3D scene frommultiple angles with a single display; further, volumetric displaysenable 3D image data to occupy real 3D space. This capability enables 3Dimage information to be shared and manipulated in a manner not possiblewith other 3D image display systems.

Despite these advantages over conventional image display systems,volumetric displays are often limited by complexity and/or cost. Thus,there is a need in the image display field to create 3D volumetricdisplays. This invention provides such new and useful displays.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a diagram view of a system of an invention embodiment;

FIG. 2A is a perspective view of anamorphic lens compression of a systemof an invention embodiment;

FIG. 2B is a top-down view of anamorphic lens compression of a system ofan invention embodiment;

FIGS. 3A and 3B are diagram views of a scattering volume of a system ofan invention embodiment;

FIG. 4 is a diagram view of a system of an invention embodiment;

FIG. 5 is a diagram view of a system of an invention embodiment;

FIG. 6 is a diagram view of a system of an invention embodiment;

FIG. 7 is an isometric view of scattering substrates of a system of aninvention embodiment;

FIG. 8A is a diagram view of non-staggered scattering planes of a systemof an invention embodiment;

FIG. 8B is a diagram view of staggered scattering planes of a system ofan invention embodiment;

FIG. 8C is a diagram view of periodically staggered scattering planes ofa system of an invention embodiment;

FIG. 9 is a diagram view of scattering substrates of a system of aninvention embodiment; and

FIG. 10 is a perspective view of a system of a variation of an inventionembodiment;

FIG. 11 is a diagram view of a dihedral corner reflecting array (DCRA);

FIG. 12 is an example view of a system of a variation of an inventionembodiment;

FIG. 13A is a front perspective view of a view restricting shield of avariation of an invention embodiment; and

FIG. 13B is a side view of a view restricting shield of a variation ofan invention embodiment.

DESCRIPTION OF THE INVENTION EMBODIMENTS

The following description of the invention embodiments of the inventionis not intended to limit the invention to these invention embodiments,but rather to enable any person skilled in the art to make and use thisinvention.

A 3D volumetric display 100 includes a light source 110 and a scatteringvolume 120, as shown in FIG. 1. The display 100 may additionally includean onboard computer 130.

The display 100 functions to enable viewers to see three-dimensionalimage data from multiple perspectives at the same time. The light source110 preferably generates light based on three-dimensional image datatransmitted to or generated by the display 100 and projects or otherwisetransmits said light to the scattering volume 120, which transforms thetransmitted light into an appropriate format for viewing. For most typesof volumetric displays, this is a complex process involving thecorrelation of three dimensional image data (which may be discretesurface models, voxel models, or any other suitable type of image datahaving three-dimensional characteristics) to the voxels (or otherdisplay units) of the volumetric display.

If the display 100 includes an onboard computer 130, the onboardcomputer 130 may convert or provide assistance in converting image datatransmitted to the display 100 into an ideal format for projection bythe light source 110. Additionally or alternatively, computers externalto the system 100 may be used to perform part or all of imageprocessing.

The light source 110 functions to generate images (i.e., light raysgenerated from image data) and transmit them to the scattering volume120 for display.

The light source 110 is preferably a planar two-dimensional displaycomprising a set of individually addressable pixels, but mayadditionally or alternatively be any suitable display. For example, thelight source 110 may comprise one or more movable light sources; e.g., alaser that may be scanned across a set of positions to simulate theappearance of multiple light sources (i.e., display multiplexing).

The light source 110 is preferably an RGB color light source (e.g., eachpixel includes red, green, and blue subpixels) but may additionally oralternatively be a substantially monochromatic light source or any otherlight source (e.g., a white light source).

The light source 110 is preferably a projector or projector light engine(e.g., DLP, laser, LCoS, and/or LCD projector) but may additionally oralternatively be any suitable display (e.g., an LCD monitor/TV display,an OLED display, etc.). In one variation of an invention embodiment, thelight source 110 includes a liquid crystal panel with a collimatedbacklight (noting that standard LCDs may not have such a collimatedbacklight).

The display 100 preferably includes a single light source 110, but mayadditionally or alternatively include multiple light sources 110. Theuse of multiple light sources 110 is discussed in more detail in thesections describing the scattering volume 120.

The light source 110 preferably includes optical elements (e.g., lenses,mirrors, waveguides) that function to couple light into the scatteringvolume 120. For example, the light source 110 may include a mirrorpositioned at 45 degrees relative to the light source 110 output(resulting in a 90-degree redirection of light source output). Asanother example, the light source 110 may include a collimating lensdesigned to increase collimating of the light source 110 output. As athird example, the light source 110 may include a lens designed to scale(or otherwise distort) light source 110 output (e.g., reduce in size orincrease in size). Such a lens may scale light source 110 outputuniformly (e.g., 2× decrease in both image dimensions) or non-uniformly(e.g., no decrease in first image dimension, 4× decrease in other imagedimension). As a fourth example, the light source 110 may include a lensthat manipulates the focal plane of the viewed image; such a lens may betunable (allowing depth of field to be swept). If such a lens weretunable at a high rate, this may provide an expanded perceived depth offield to a viewer.

In one implementation of an invention embodiment, the light source 110includes an anamorphic lens that spatially compresses the light outputof the light source along a single axis perpendicular to the opticalaxis of the light source 110, as shown in FIG. 2A (perspective view) andFIG. 2B (top-down view). The anamorphic lens may be any suitable lenscapable of scaling an image from the light source anisotropically (e.g.,a three-element cylindrical lens). In this implementation, thescattering volume 120 preferably expands the distorted intermediateimage produced by the anamorphic lens, restoring the original aspectratio of the source image prior to scattering the image. In thisimplementation, pixel compression enables either higher resolution perimage slice (discussed in more detail later), more image slices per agiven height resolution, or an intermediate combination of these two.

Note that while anamorphic lenses have been used in prior art volumetricdisplays, such prior art implementations use the anamorphic lens toeither increase resolution of a volumetric image or to generate imagesthat appear different from different angles (e.g., via use of alenticular lens array). In particular, note that these uses do notinvolve a scattering volume 120 that distorts the image produced by theanamorphic lens to restore the original aspect ratio of the image (priorto the anamorphic lens). While the anamorphic lens of the light source110 may alternatively be used for any purpose, it is preferably pairedwith a scattering volume 120 that restores the original aspect ratio (orotherwise performs scale distortion). This is discussed in more detailin the sections covering the scattering volume 120.

The light source 110 may additionally or alternatively include anypassive or active optical elements to prepare light for the scatteringvolume 120 or for any other purpose. For example, the light source 110may include filters or splitters.

The scattering volume 120 functions to scatter light emitted by thelight source 110 in such a manner that the scattered light forms athree-dimensional image viewable by multiple individuals at multipleperspectives substantially simultaneously.

The scattering volume 120 preferably includes sets of scatteringelements 121 arranged on scattering substrates 122 disposed within thevolume 120, as shown in FIG. 3A. Additionally or alternatively, thescattering volume 120 may comprise scattering elements 121 disposedwithin a solid substrate (and not arranged on a set of scatteringsubstrates 122), as shown in FIG. 3B, suspended or otherwise positioned(e.g., without use of a solid substrate). For example, the scatteringvolume 120 may comprise a volume filled with fog or other air-suspendedparticles (e.g., glycol vapor, atomized mineral oil).

The scattering elements 121 function to scatter light emitted by thelight source 110 in such a manner that light scattered by a scatteringelement 121 appears to have originated (from a viewer's perspective)from the scattering element 121. By arranging scattering elements 121 inthree-dimensional space, a three-dimensional image may be formed; eachscattering element 121 may represent a scattering point/area similar toone that may be found on a real object (as opposed to an image projectedwithin the scattering volume 120).

Scattering elements 121 may take a variety of forms. In a firstimplementation of an invention embodiment, scattering elements areformed by printing or otherwise depositing low-opacity ink upon asurface of a scattering substrate 122. In a second implementation of aninvention embodiment, scattering elements 121 are cavities etched into ascattering substrate 122 or otherwise within the volume 120 (this may bealternatively phrased as a volume with a relative index of approximately1 and/or an air containing volume if the volume is filled with air; notethat here “volume” refers to the scattering element 121 and not thescattering volume 120). Additionally or alternatively, scatteringelements 121 may be formed in any manner that results in a change ofindex of refraction within the scattering volume 120. For example, ascattering element 121 may have a solid/liquid region of some index n₂within a scattering volume 120 substantially having an index n₁ (e.g.,enabled by metallic nanoparticles or quantum dots embedded in the volume120).

Scattering elements 121 may take any shape or form. For example,scattering elements 121 may be conical volumes, rectangular prismaticvolumes, irregular volumes and/or spherical volumes. In the case ofprinted scattering elements 121, the shape of the scattering element maybe determined by printing methods, for instance (other potential factorsmay include the shape and surface of the scattering substrates 122,surface treatments, etc.)

The shape and form of the scattering elements 121, as well as theirorientation relative to light originating from the light source 110, maydetermine the scattering direction of light incident upon the scatteringelements 121. For example, light may be scattered isotropically oranisotropically by scattering elements 121.

The surface of the volume defining a scattering element 121 mayadditionally play an important role in how light is scattered.Scattering elements 121 may be smooth (which may result in more specularreflection) or textured (which may result in more diffuse reflection).Further, scattering element 121 surfaces may be coated (e.g., with ananti-reflective coating, with a fluorescent coating, with a metalliccoating, etc.) to further adjust the light scattering properties of thescattering elements 121.

The scattering properties of scattering elements 121 may be dependent ona number of characteristics of light emitted by the light source 110. Aspreviously mentioned, the position and orientation of a scatteringelement 121 may determine how light is scattered by a scattering element121. Additionally or alternatively, scattering properties may beaffected by light frequency and/or light polarization. For example, ascattering element 121 may scatter light of one polarization in a firstdirection, while the same element 121 may scatter light of anotherpolarization in a second direction. As another example, a scatteringelement 121 comprising a metallic nanoparticle may scatter lightselectively based on frequency (e.g., scattering light of a narrowfrequency band while not affecting light outside that band). Scatteringelements 121 may additionally or alternatively be affected by otherenvironmental variables; e.g., temperature, pressure applied to thescattering volume 120 (e.g., if the volume 120 contains piezoelectricmaterial), applied electric field, applied magnetic field, etc.

In a variation of an invention embodiment, scattering elements 121 arecoated with or otherwise comprise fluorescent material (e.g., printedusing fluorescent ink), such that when light above a certain thresholdfrequency impinges upon the elements 121, the scattering elements 121fluoresce at some particular frequency (or set of frequencies).Scattering elements 121 may be coated partially with fluorescentmaterial (e.g., to provide directionality for light emitted by thefluorescing elements 121).

In a first implementation of an invention embodiment, the scatteringelements 121 are preferably printed upon scattering substrates 122. Inthis implementation (henceforth referred to as a printedimplementation), the scattering elements 121 are preferably printed on ascattering substrate using a subtractive process; e.g., a layer of inkis deposited upon a surface of a scattering substrate 122, and ink isselectively removed from the surface of the scattering substrate 122until a desired pattern of scattering elements 121 is exposed.Alternatively, the scattering elements 121 may be printed using anadditive process; e.g., ink is deposited on the surface of a scatteringelement in places where scattering elements 121 are desired and not inplaces where ink is not intended to be. The scattering elements 121 mayadditionally or alternatively be deposited or otherwise fabricated usingany process. Some examples of processes that may be used to depositscattering elements 121 include letterpress printing, offset printing,gravure printing, flexographic printing, dye-sublimation printing,inkjet printing, laser printing, pad printing, relief printing, screenprinting, intaglio, thermal printing, electron beam deposition, ion beamdeposition, atomic layer deposition (ALD), chemical vapor deposition(CVD), physical vapor deposition (PVD), sputtering, thermal evaporation,electron beam evaporation, and electroplating.

In the printed implementation, the deposited ink may be any substance(e.g., organic polymer, metal, inorganic compound). In one exampleimplementation, the deposited ink is a white-colored UV-curable polymer.

In the printed implementation, the scattering elements 121 may be of anyshape and volume, as previously described. The ink deposition process(or subsequent processing of the scattering elements 121) may dictate,in part, the shape of the of the scattering elements 121. For example, ascattering element 121 with a two-dimensional profile in the plane ofthe scattering substrate 122 (e.g., a circle) may have varyingcharacteristics in the axis perpendicular to the surface of thescattering substrate (e.g., the circle may correspond to a dome-shapedelement 121, a cylindrical element 121, etc.). Likewise, the scatteringelements 121 may have any surface properties, as previously discussed.

In the printed implementation, the scattering elements 121 preferablyallow substantial transmission of light (i.e., they are low-opacity),but may additionally or alternatively allow any amount (including none)of light transmission. The scattering elements 121 may achievetransmission of light in any manner; for example, the elements 121 maybe formed by a thin deposition of an ink that is substantially opaque,but only at thickness substantially greater than the depositionthickness. As a second example, the elements 121 may be formed of an inkthat is substantially transparent or translucent even at highthicknesses (e.g., greater than 1 cm). As a third example, the elements121 may be formed using halftoning or a similar process wherein multipleinks of different opacities (e.g., one opaque and one transparent) arealternated in a pattern to give the effect of uniform low-opacity to thehuman eye.

In a second implementation of an invention embodiment, the scatteringelements 121 are preferably formed by creating cavities in a solidmaterial (e.g., the material of a scattering substrate 122, or thematerial of the scattering volume 120 if there are no distinctscattering substrates 122). In this implementation (henceforth referredto as the engraved implementation), scattering elements 121 may beformed in any manner; e.g., via laser subsurface engraving. Subsurfacelaser engraving may be performed, for instance, by a focused laserimpinging on a face of the scattering volume 120 (the light axis normalto the face), where the focus of the laser determines the engravinglocation. Note that if scattering elements 121 are formed usingsubsurface engraving, scattering elements 121 may be formed usingmultiple passes (with each pass resulting in subsurface engraving at thesame position or at nearby positions). With single-pass subsurfaceinduced damage, there is typically strong scattering from 2 directions.More uniform scattering may be achieved through all scattering planes ofa 3D scattering volume 120 by performing three laser-induced engravingpasses, each pass through the two lasers doing the engraving at a 90/90degree rotation from the previous pass (e.g., rotating 90 degrees in onerotational axis and 90 degrees in a second rotational axis, where thesetwo rotational axes are orthogonal to each other and to the light axisof the subsurface engraving laser). This process results in groups ofthree scattering elements 120 located near each other (or at the samelocation) by way of 3 orientations of the scattering volume 120 in thelaser etching step. These orientations are preferably orthogonal but mayalternatively be related to each other in any manner. In one example,the three orientations correspond to the orientations of faces of thescattering volume 120. In this example, the three scattering elementsmay scatter light out of each face, resulting in a perception ofomni-directional scattering (despite having individually directionalscattering elements). Note that is a technique for creating subvoxelgroups (described in more detail in later sections).

In the engraved implementation (similar to the printed implementation),the scattering elements 121 may be of any shape and volume, aspreviously described. The cavity formation process may dictate, in part,the shape of the of the scattering elements 121. For example, ascattering element 121 with a two-dimensional profile in the plane ofthe scattering substrate 122 or scattering volume 120 (e.g., a circle)may have varying characteristics in the axis perpendicular to thesurface of the scattering substrate (e.g., the circle may correspond toa dome-shaped element 121, a cylindrical element 121, etc.). Likewise,the scattering elements 121 may have any surface properties, aspreviously discussed.

The scattering substrates 122, if present, function to provide surfacesfor the scattering elements 121 to be printed or otherwise created. Thescattering substrates 122 may be formed of any solid material. Thescattering substrates 122 are preferably substantially transparent, butmay additionally or alternatively have any optical properties.

Scattering elements 121 are preferably disposed upon one or moresurfaces of the scattering substrates 122, but may additionally oralternatively be positioned anywhere within the scattering volume 120(e.g., inside scattering substrates 121 as opposed to on the surface,inside a volume 120 not containing substrates 122). For example, ascattering element 121 may be printed upon one or both sides of apolymer sheet substrate 122.

In a variation of an invention embodiment, substrates 122 or volumes 120may be processed (before, during, or after element 121 deposition) toenhance or modify scattering for elements 121. For example, scatteringelements 121 may be printed into grooves, pockets, domes, pyramids etc.etched, deposited, or otherwise shaped on the surface of a scatteringsubstrate 122. As another example, scattering substrates 122 may becoated with anti-reflective coatings to modify how light enters and/orexits the substrates 122.

In a variation of an invention embodiment, substrates 122 may be clad,sandwiched, and/or otherwise coupled to ‘carrier substrates’ (e.g., ascattering substrate having scattering elements on its surfaces may becoupled to carrier substrates on both sides of the substrate 122).

Scattering elements 121 are preferably arranged upon one or moresurfaces of a scattering substrate 122 (or otherwise within a scatteringvolume 120) in a geometric pattern, but may additionally oralternatively be arranged in any manner.

Similar to scattering elements 121, scattering substrates 122 may haveany shape and/or surface qualities. In one example embodiment,scattering substrates 121 are thin polymer sheets. In a second exampleembodiment, scattering substrates 121 are thicker trapezoidal prisms(which may, for example, be injection molded or machined). Thescattering substrates 121 of a volume 120 may be identical (e.g., thescattering volume 120 may include four identical polymer sheets) or mayalternatively be non-identical (e.g., the scattering volume 120 containsa set of trapezoidal prisms with optically complementary shapes,discussed in detail in later sections). Likewise, the pattern orpresence of elements 121 on a substrate 122 may be identical ornon-identical to the pattern of presence of elements 121 on anothersubstrate 122.

The scattering substrates 122 are preferably mounted within thescattering volume 120, but may additionally or alternatively bepositioned within the scattering volume 120 in any manner. For example,the scattering volume 120 may comprise a set of scattering substratesadhered together (without additional supporting material).

As previously mentioned, the scattering elements 121 are preferablyarranged in a geometric pattern on the substrates 122. This pattern,along with the shape and position of the scattering substrates 122within the scattering volume 120 (and the optical properties of thescattering elements 121 and substrates 122, the substrate of thescattering volume 120, etc.), encodes a relationship between pixels (orother two-dimensional areas) of the light source 110 and scatteringelements 121.

In one implementation of an invention embodiment, scattering elements121 may be encoded 1:1 with light source 110 pixels (i.e., eachscattering element 121 corresponds to a pixel of the light source 110).Alternatively, this may be stated as a 1:1 voxel:pixel relationship.

Additionally or alternatively, multiple scattering elements 121 may beassociated with a single light source 110 pixel (i.e., many-to-onevoxel:pixel relationship). In one implementation of an inventionembodiment, several scattering elements 121 are positioned to scatterlight from a single light source 110 pixel. These scattering elements121 may be grouped closely; in such a case, they may be referred to assubvoxels. Subvoxels may be grouped into voxels for many reasons; forexample, each subvoxel of a voxel may have different frequency response(similar to how each pixel of the light source 110 may include red,green, and blue subpixels). As another example, each subvoxel may havedifferent scattering properties (e.g., four subvoxels with 90 degreescattering angles are oriented to provide 360 degree scattering for alight source 110 pixel). Note that a group of subvoxels corresponding toa voxel may be referred to as a voxel group.

The spacing between voxels/voxel groups is preferably substantiallygreater than the spacing between subvoxels/scattering elements 121within a voxel group. For example, the minimum spacing of voxel groupsmay be more than twice (or any factor) the maximum spacing of subvoxelswithin a voxel group.

Alternatively, multiple scattering elements 121 associated with a pixelneed not necessarily be grouped closely (i.e., they may not serve assubvoxels). For example, scattering elements 121 may be positionedwithin the path of a ray emitted by the light source 110; if a firstelement 121 transmits some of the light, that transmitted light may bescattered by additional elements 121 within the path even if they arenot necessarily close to each other in space.

Additionally or alternatively, multiple pixels of the light source 110may correspond to a single scattering element 121 (i.e., one-to-manyvoxel:pixel relationship). This may be of particular interest in caseswhere the pixel size is smaller than the size of the scattering element121.

As previously stated, scattering elements 121 are preferably disposedwithin the scattering volume 120 in a geometric pattern (e.g., accordingto a three-dimensional rectangular grid). Alternatively, scatteringelements 121 may be arranged in any manner.

The scattering volume 120 is preferably a transparent solid (includingscattering elements 121 and substrates 122) but may additionally oralternatively have any opacity and be made of any material.

The scattering volume 120 is preferably a rectangular prism, but mayadditionally or alternatively be any shape or form.

The scattering volume 120 may be formed by any method. In one exampleembodiment, the scattering volume 120 is a transparent hollowrectangular volume. In this embodiment, the scattering substrates 122are placed within the volume 120. The scattering substrates 122preferably have an index of refraction similar to the scattering volume120, and further, the hollow space of the volume 120 not occupied by thesubstrates 122 is preferably filled with an index-matching material(e.g., a liquid, a resin, etc. having a similar index of refraction tothat of the substrates 122 and/or the rest of the volume 120); e.g., toreduce reflection at interfaces within the volume 120. Alternatively,the scattering volume 120 may have any suitable properties.

In a variation of an invention embodiment, the scattering substrates 122have a different index of refraction than the material surrounding thesubstrates 122. For example, the scattering substrates 122 may have ahigher index of refraction than a surrounding fluid, enabling thesubstrates 122 to serve as a waveguide for light entering the scatteringvolume 120.

In a first implementation of an invention embodiment, the scatteringsubstrates 122 are thin sheets arranged in a tilted planar configurationand scattering elements 121 are arranged in a rectangular grid patternon one surface of the substrates 122, as shown in FIG. 3A (which showsfour tilted planes). In this implementation, images projected by thelight source are preferably grouped into image “slices” corresponding tothe position of each tilted plane. In one implementation of an inventionembodiment, each slice is transmitted by a single light source 110, asshown in FIG. 4.

In a second implementation of an invention embodiment, slices aretransmitted by multiple light sources 110, as shown in FIG. 5. Oneadvantage to a single light source 110 is reduction in cost andcomplexity; however, resolution is lost when slices are compressed(since the light source 110 has a finite pixel density). The use ofmultiple light sources 110 and transforming lenses results in apreservation of resolution.

In a third implementation of an invention embodiment, an anamorphic lensis used to anisotropically compress the output of the light source 110(creating a modified aspect ratio), and the scattering volume 120contains scattering elements 121 arranged such that the original aspectratio is restored by the scattering volume 120, as shown in FIG. 6. Inan example of the third implementation, a light source 110 may have anoutput image size x₀×y₀ and an aspect ratio of x₀:y₀. An anamorphic lensis used to modify the output image size to x₁×y₁ and therefore an aspectratio of x₁:y₁. In this example, the modified image size is such thatk(x₁:y₁)=x₀:y₀; k<1 (in other words, the x dimension has been compressedrelative to the y dimension, where k is referred to as a modificationfactor). The array of scattering elements 121 of the scattering volume120 then may have dimensions x₁×y₁×z₁, where

${z_{1}^{2} \approx {\Delta^{2}\left( {\frac{1}{k^{2}} - 1} \right)}},$

thus restoring the original aspect ratio. To show how this follows, onecan write

${{a_{1}x_{1} \times a_{2}y_{1}} = {x_{0} \times y_{0}}};{k = {\frac{a_{1}}{a_{2}}.}}$

For the two dimensional representation of a slice with ‘thickness’ Δ torestore the original aspect ratio it must be divided by k; i.e.,

$\left( \frac{\Delta}{k} \right)^{2} = {\left. {\Delta^{2} + z^{2}}\rightarrow z \right. = {\Delta {\sqrt{\left( \frac{1}{k} \right)^{2} - 1}.}}}$

In the case where the scattering volume 120 has n slices of equal width,

$z = {\frac{x_{1}}{n}{\sqrt{\left( \frac{1}{k} \right)^{2} - 1}.}}$

In the case where the y dimension is not expanded or compressed (i.e.,a₁=k, a₂=1),

$z = {{\frac{k}{n}x_{0}\sqrt{\left( \frac{1}{k} \right)^{2} - 1}} = {\frac{1}{n}x_{0}{\sqrt{1 - k^{2}}.}}}$

In a fourth implementation of an invention embodiment, the scatteringsubstrates 122 are varying-shape trapezoidal prisms arranged in avarying-tilt configuration and scattering elements 121 are arranged in arectangular grid pattern on one or both large surfaces of the substrates122, as shown in FIG. 7. Similar to the previous implementation, in thisimplementation, images projected by the light source are preferablygrouped into image “slices”.

The scattering elements 121 may additionally or alternatively bearranged in any manner. For example, scattering elements 121 may bearranged in a random pattern. As another example, scattering elements121 may be grouped into lines.

The dimensions of the scattering elements 121 are preferably such thatthe spacing between elements 121 is multiple times larger than the width(or other dimension) of the elements 121; alternatively, the ratiobetween element 121 dimensions and spacing may be any ratio. Forexample, in the case where scattering elements 121 are grouped intolines (e.g., parallel to the scattering plane and to each other), thelines may be separated by a distance multiple times (e.g., five) largerthan the line thickness. In this case, the distance between elementsalong a line is preferably less than the distance between lines (e.g., ⅕the distance between lines). Alternatively, distance between elementswithin a line may be any value. This may be important for preventingloss of resolution for ‘deeper’ scattering substrates 122. Further,element 121 arrangement may be staggered (or otherwise varied) acrosssubstrates 122. In a non-staggered arrangement, the scattering lines ofeach scattering plane are positioned at the same height (i.e., Δz=0), asshown in FIG. 8A. In a staggered arrangement, the scattering lines ofeach scattering plane may be shifted relative to each other (i.e.,Δz>0), as shown in FIG. 8B. In a periodically staggered arrangement, asshown in FIG. 8C, each scattering plane is shifted relative to itsneighbors, but the shifts repeat periodically.

Likewise, the scattering substrates 122 may be arranged in any manner;e.g., the substrates 122 may be tilted in a conical configuration. Anexample of a conical configuration includes a set of substrates 122arranged such that the top edge of the substrates 122 (relative to theaxis of projected light) forms a circle around the light axis, as doesthe bottom edge of the substrates 122, but the circles are differentsizes.

The scattering substrates 122 are preferably positioned staticallywithin the scattering volume 120 but may additionally or alternativelybe movable (e.g., if the scattering substrates 122 are suspended in afluid). Additionally or alternatively, the scattering substrates 122 maynot be movable, but may be reconfigured (i.e., the scattering propertiesof the elements 121 or substrates 122 may be changed) due to appliedlight, electric field, magnetic field, heat, pressure, or any otherfactor.

For example, scattering elements 121 or substrates 122 may bereconfigured to optimize for different light sources 110, for differentdisplayed scenes, and/or for different ambient light conditions.

The scattering volume 120 preferably has a single light entry surface(i.e., light from light sources 110 enters only at a single surface),but may additionally or alternatively have multiple light entrysurfaces. In instances where the scattering volume 120 includes multiplelight entry surfaces (or more generally, for any reason), the scatteringvolume 120 may include multiple sets of scattering substrates 121configured to scatter light entering at different surfaces, as shown inFIG. 9.

In one variation of an invention embodiment, the scattering volume 120includes waveguides (or other optical elements) between a light entrysurface and light scattering elements 121.

In a second variation of an invention embodiment, the scattering volume120 is coupled to a dihedral corner reflective array (DCRA) 122 or aDCRA 122 is otherwise positioned above one or more surfaces of thescattering volume 120.

The DCRA 122 preferably functions to generate a real image of thevolumetric display 100; that is, the DCRA 122 functions to replicate theimage displayed inside the scattering volume 120 in a volume exterior tothe scattering volume, as shown in FIG. 10. Additionally oralternatively, the DCRA 122 may function to generate a real image of thevolumetric display in any space.

In this variation, the DCRA 122 preferably comprises a two-dimensionalarray of dihedral corner reflecting elements positioned such that lightexiting the scattering volume 120 is able to reflect twice inside thereflecting elements, resulting in the light traveling along a pathplane-symmetric to incident path, as shown in FIG. 11.

The DCRA 122 is preferably fabricated by milling, etching, or otherwisecreating an array of square through holes in a highly reflectivesubstrate or film (e.g., a metal), but may additionally or alternativelybe fabricated by any suitable means. More details surrounding DCRAfabrication and material properties may be found in “Floating volumetricimage formation using a dihedral corner reflector array device”¹, theentirety of which is incorporated by this reference. ¹Daisuke Miyazki etal., 1 Jan. 2013/Vol. 52, No. 1/APPLIED OPTICS

While the DCRA 122 as described in the incorporated reference is aplanar (i.e., all of the reflecting elements are contained within aplane), the DCRA 122 of the present invention may be of any shape ororientation. For example, the display 100 may include a DCRA 122comprising an array of reflecting elements milled from a dome-shapedfilm instead of a planar one (e.g., a film that approximates a sphericalsurface). Likewise, while the DCRA 122 preferably includes rectangularprism-based reflectors, the DCRA 122 may additionally or alternativelyinclude any suitable type of reflector capable of reflecting lighttwice, resulting in a plane-symmetric real image.

The DCRA 122 is preferably aligned with the scattering volume 120 suchthat the majority of light emitted by the volumetric display 100 isaccepted by the DCRA 122 (that is, the angle of the light with respectto the DCRA 122 is such that the light contributes to the formation of aplane-symmetric real image), as shown in FIG. 12. Additionally oralternatively, optics (e.g., lenses, mirrors, etc.) may be used in thelight path in between the DCRA 122 and the scattering volume 120 toimprove or otherwise modify acceptance of light emitted from thescattering volume 120. In one implementation of the variation, thescattering volume 120 preferably includes highly directional lightscattering elements 121, and the DCRA 122 is configured to accept themajority of light emitted by the elements 121.

In a second variation of an invention embodiment, the scattering volume120 includes a filter (e.g., a filter that restricts viewing angle) toreduce the perception of misalignment when the scattering volume 120 isviewed at extreme angles (e.g., >45 degrees from center). Such a filtermay be coupled to the scattering volume 120 in any manner (e.g., aprivacy film may be applied to the exterior of the volume 120). Thevolume 120 may alternatively include any elements capable of restrictingviewing angle for purposes of preventing perception of misaligned voxels(e.g., filters, concave lenses, other lenses, etc.). For example, thescattering volume 120 may include an opaque or partially opaque shieldto restrict viewing angle to reduce the perception of misalignment whenthe scattering volume 120 is viewed at extreme angles (e.g., >45 degreesfrom center), as shown in FIG. 13A and FIG. 13B. The shape and structureof the shield may be designed based on the maximum viewing angle desired(e.g., a shield designed to restrict viewing angle to ninety degrees maystick out past the surface of the scattering volume 120 farther than ashield designed to restrict viewing angle to 120 degrees). The shieldmay have any structure and be fabricated of any suitable material suchthat viewing of the scattering volume 120 is not substantially impededwithin a desired viewing angle, and viewing is impeded (partially orfully) outside of that viewing angle.

The scattering volume 120 is preferably stationary; additionally oralternatively, the scattering volume 120 may move with the light source110. For example, the scattering volume 120 may be rotated along withthe light source 110 quickly to scatter light in multiple desireddirections if the light is not scattered in all desired directions whilethe scattering volume 120 is stationary.

Additionally or alternatively, the scattering volume 120 may be movedrelative to the light source 110 (whether the light source 110 is movedor not) to modify the relationship between scattering elements 121 andpixels of the light source 110.

If the scattering volume substrate comprises multiple layers (or isotherwise modular), those layers or modular pieces may be moved orotherwise reoriented relative to each other to modify the lightscattering properties of the scattering volume 120.

Note that the scattering volume 120 may include optical elements (e.g.,mirrors, lenses, waveguides) or other light-altering treatments (e.g.,anti-glare surface treatments or layers, viewing angle restrictiontreatments or layers).

The onboard computer 130 functions to perform image processing for imagedata received by the display 100 prior to display by the light source110. For example, the onboard computer may separate 3D model informationinto slices to be projected by the light source 110. The onboardcomputer 130 may additionally or alternatively function to prepare 3Dimage data for voxel representation in any manner. For example, if lightfolding is performed by the display 100 (i.e., images are sliced andanisotropically scaled), the onboard computer 130 may performinterpolation between pixel values to determine a new transformed pixelvalue. As another example, the onboard computer 130 may performdithering to simulate blurring at image edges.

In the case of a volumetric display where the display involves a seriesof scattering elements arranged in ‘slices’ (e.g., the display 100),this image processing involves at a minimum converting the input imagedata into a series of two dimensional representations (image slices) andprojecting those image slices onto the scattering elements 121.Traditionally, such image slices are created by splitting the inputimage data into a set of spatial partitions (typically along the ‘depth’axis) and flattening (or otherwise processing) input image data withineach partition into a two-dimensional image, which is then projected ona scattering plane corresponding to that spatial partition. Thesespatial partitions are preferably unique (i.e., different for eachslice) but may be overlapping. Alternatively, spatial partitions may bedesignated in any manner.

The onboard computer 130 preferably processes input image data intoslices based on the unique scattering parameters of a givenimplementation of the scattering volume 120 (and potentially also basedon desired optical properties of the output image, such as viewingcone).

Scattering parameters are preferably parameters that describe thespatial relationship between the scattering elements of the volume 120and the light source 110. For example, scattering parameters maydescribe the thickness of each of a set of scattering substratesarranged within the display volume. In another example, scatteringparameters can include the orientation angle theta (θ) and relativedisplacement delta (Δ) of each of the scattering substrates, as shown inFIG. 4 (as well as the location of scattering elements within eachsubstrate). However, scattering parameters can be any other suitableparameters related to how light is scattered by the display volume.

Scattering parameters can additionally or alternatively parameterize therelationship between the light source 110 of the system 100 and thevolume 120 in which the three dimensional image is displayed. Inparticular, scattering parameters preferably include parameters definingthe mapping between pixels of the light source and voxels of the displayvolume. These parameters may be based on the geometric arrangement ofthe scattering elements of the display, but can alternatively be basedon the orientation of the light source or on any other suitable aspectof the display configuration. In some variations, the light sourceoutput 110 may be divided into two-dimensional slices, each of whichmaps to a three dimensional slice (e.g., an image slice), in such casesthe scattering parameters may describe the mapping between thetwo-dimensional and three-dimensional slices.

Scattering parameters may include orientation data describing therelative spacing and position of a set of scattering substrates 122. Thescattering substrates can be arranged in a planar configuration, or inany other suitable configuration. In this variation, orientation datapreferably includes the linear distance separating each substrate, aswell as the angular position of each of the set of substrates relativeto the light source 110. The substrates are each preferably separated bythe same relative spacing, but alternatively can have any suitablerelative spacing (e.g., each substrate may be separated from adjacentsubstrates by a different relative spacing). Likewise, each substratepreferably has the same angular position relative to the light source110, but can alternatively have any suitable angular position. Thisorientation data is preferably used in conjunction with light source 110data to determine a relationship between pixels of the light source 110and voxels of the display. Scattering parameters can additionally oralternatively be any suitable parameters related to the manner in whichlight is generated and scattered by the display to form the volumetricimage.

Optical properties of the output image are preferably properties relatedto how the volumetric image can be perceived by a viewer of the display.These can include: opacity, color, hue, saturation, transparency,maximum viewing angle, minimum viewing angle, maximum and/or minimumviewing cone, or any other suitable property of the displayed image.

As previously mentioned, the onboard computer 130 preferably determinesthe output of the light source 110 based on the received display model,and can additionally or alternatively function to do so according to thereceived desired optical properties and scattering parameters.Determining image slices of the display model may also be referred to asslicing. Slicing can additionally or alternatively function to compute acollection of 2D planes (e.g., the 2D planes in a volumetric display)that represents the 3D geometry of the display model when displayed.

An image slice as described herein is preferably one of a number of suchslices that together make up a volumetric representation of the displaymodel once suitably displayed. Note that an image slice can beconsidered as the set of voxels constituting a planar section of thedisplayed volumetric image, or equivalently as the set of pixels of thelight source 110 corresponding to that set of voxels when operating thedisplay. The image slice may additionally or alternatively be consideredas the virtual representation (e.g., as stored data) of the image slice.Additionally or alternatively, the image slice can be any suitable realor virtual construct ultimately rendered as a portion of the volumetricimage at the display.

The determination of image slices affects the optical properties of thedisplayed image, such as those discussed above in relation to thedesired optical properties. For example, the spacing between imageslices (e.g., the physical spacing in the display, the choice of spacingmade, etc.) can affect the maximum view angle or view cone of avolumetric 3D image.

The onboard computer 130 preferably performs transformation of inputimage data into output image slices by splitting input image data (e.g.,3D model) into a set of partitions (‘slice regions’). For a slice-basedvolumetric display, these partitions are preferably along the preferredviewing axis of the display; however, the partitions may additionally oralternatively be made along any axis. Note that creating partitions inthe input image data along an axis of the volumetric display requiresthat the input image data be projected into a spatial representative ofthe volumetric display, henceforth referred to as the projection space(e.g., if the volumetric display is a cube, where and how the image datais projected ideally within the cube).

The onboard computer 130 preferably determines the slice regions basedon the correspondence of this ideal three-dimensional projection withinthe scattering space to the location of scattering element planes withinthat space. For example, if a scattering display includes ten scatteringelement planes, the computer 130 preferably functions to subdivide theprojection space into ten slice regions. Note that the size and locationof these slice regions is preferably determined by the location andspacing of scattering elements within the volumetric display; forexample, if scattering planes are more closely spaced in one region of avolumetric display, the slice regions corresponding to that region (ofthe projection space) may be smaller (i.e., the distance along thepartitioning axis is shorter).

Additionally or alternatively, slice regions may be chosen in anymanner. For example, slice regions may be further based on input imagecontent. If, for example, a non-transparent sphere is to be displayedand a viewer is limited in view, it may be desirable to focus on theaspects of the sphere that are intended to be visible (rather than theentire sphere). In this instance, the ‘visible projection space’ may besubdivided rather than the entire projection space. Note that in thisparticular example, the onboard computer 130 may perform additionalimage modification to account for depth discrepancy; that is, if onlythe visible half of the sphere is displayed, but it is displayed acrossthe entire scattering volume, the input image data must be scaled toaccount for the stretching along the depth axis that would occur if halfof the projection space were displayed across the entire scatteringvolume naively.

After the slice regions are determined, the onboard computer 130preferably creates a two-dimensional representation of thethree-dimensional image data within each slice region. This ispreferably accomplished by ‘flattening’ the three-dimensional image dataonto a two-dimensional plane with respect to the viewing axis (i.e., allx,y,z, data is converted to x,y; if image data occupies the same x and ycomponents, the image data with a z component closer to the front of thedisplay is shown assuming that the image data is non-transparent; if theimage data has transparency, it is preferably combined using alphacompositing). Note that if that a composited pixel has a less than one(i.e., not fully opaque), the composited pixel may be displayed assemi-transparent by lowering brightness, altering display duty cycle, orin any other manner. For example, transparency of an image region (asopposed to an individual pixel) may be represented using bitmaptechniques. Additionally or alternatively, the onboard computer 130 maytransform the three-dimensional image data into two-dimensional slicesin any manner.

The onboard computer 130 may additionally or alternatively function tocontrol general properties of the light source 110; for example, theonboard computer 130 may control brightness of light source 110 pixelsto simulate changes of opacity in a displayed image.

Additionally or alternatively, if the scattering volume 120 isreconfigurable, the onboard computer 130 may function to provide controlinformation to the scattering volume 120 (e.g., directing theapplication of electric field to affect scattering properties ofmetallic nanoparticles, moving scattering substrates 122, etc.).

In one variation of an invention embodiment, the onboard computer 130may perform multiplexing of ‘virtual slices’ in order to simulate higherdepth resolution. For example, a 3D animation at 60 FPS may be slicedinto 12 depth slices; alternating slices of the 12 may be displayed witha scattering volume 120 having only six tilted planes, resulting in a 30FPS 3D animation (with a simulated depth resolution of 12 slices asopposed to 6).

In another variation of an invention embodiment, the onboard computer130 may perform attenuation-based light field image synthesis togenerate or modify image slice data, as described in “Synthesis forAttenuation-based Light Field and High Dynamic Range Displays”², whichis incorporated in its entirety by this reference. ²Wetzstein, G.,Lanman, D., Heidrich, W., Raskar, R. 2011. Layered 3D: Tomographic ImageSynthesis for Attenuation-based Light Field and High Dynamic RangeDisplays. ACM Trans. Graph. 30, 4, Article 95 (July 2011), 11 pages.DOI=10.1145/1964921.1964990 http://doi.acm.org/10.1145/1964921.1964990.

Note that the functions described as performed by the onboard computer130 may additionally or alternatively be performed by any other computersystem (e.g., a distributed computing system in the cloud).

In one implementation of an invention embodiment, the onboard computer130 is communicative with another electronic device (e.g., a smartphone,a tablet, a laptop computer, a desktop computer, etc.) over a wiredand/or wireless communication connection. In this implementation, datamay be streamed or otherwise communicated between the onboard computer130 and the other electronic device. For example, a smartphone maytransmit video information to the onboard computer, where it is slicedinto depth slices by the onboard computer 130. Additionally oralternatively, depth slicing may be performed by the other electronicdevice. In general, the task of image processing may be performed and/orsplit between any number of electronic devices communicative with theonboard computer 130.

The display 100 may also include means for interaction tracking. Forexample, the display 100 may include a depth camera that tracks userinteraction with the display 100, allowing control and/or manipulationof the image displayed based on gestures and/or other interactionbetween a viewer and the display 100 as measured by the depth camera. Asanother example, the display 100 may include a transparent touch sensorthat tracks viewer touch interactions on surfaces of the scatteringvolume 120.

In one variation of an invention embodiment, the display 100 may trackviewer touch interaction based on changes in light scattering of thescattering volume 120 due to frustrated total internal reflection. Thisconcept is described in more detail in U.S. Provisional Application No.62/075,736, the entirety of which is incorporated by this reference.

As a person skilled in the art will recognize from the previous detaileddescription and from the figures and claims, modifications and changescan be made to the invention embodiments of the invention withoutdeparting from the scope of this invention defined in the followingclaims.

What is claimed is:
 1. A three-dimensional volumetric displaycomprising: a light source that generates a two-dimensional imageoutput; a substantially transparent scattering volume, coupled to thelight source on a first face of the scattering volume, that scatters theimage output of the light source in a direction perpendicular to thelight axis of the output of the light source; wherein the scatteringvolume comprises a three-dimensional array of scattering elements, thethree-dimensional array of scattering elements arranged in a pluralityof scattering planes tilted relative to the first face of the scatteringvolume; an anamorphic lens optically located between the light sourceand the scattering volume; wherein the anamorphic lens transforms thetwo-dimensional image output generated by the light source such that anaspect ratio of the image output is modified, by a modification factor,from an original aspect ratio to a transformed aspect ratio; and anonboard computer; wherein the onboard computer determines a set of slicepartitions of a three-dimensional image dataset according to scatteringparameters of the scattering volume and transforms the three-dimensionalimage dataset into the two-dimensional image output according to theslice partitions; wherein the image output comprises a set of imageslices; each image slice of the set corresponding to a unique spatialpartition of a three-dimensional image dataset; each image slice of theset projected onto a plane of the plurality of scattering planes.
 2. Thevolumetric display of claim 1, wherein the light source comprises adigital mirror display.
 3. The volumetric display of claim 2, whereinthe volumetric display has a one-to-one voxel to pixel relationship. 4.The volumetric display of claim 3, further comprising a dihedral cornerreflective array (DCRA) coupled to a surface of the scattering volume;wherein the DCRA creates a real image of a three-dimensional imagedisplayed within the scattering volume.
 5. A three-dimensionalvolumetric display comprising: a light source that generates atwo-dimensional image output; and a substantially transparent scatteringvolume, coupled to the light source on a first face of the scatteringvolume, that scatters the image output of the light source in adirection perpendicular to the light axis of the output of the lightsource; wherein the scattering volume comprises a three-dimensionalarray of scattering elements, the three-dimensional array of scatteringelements arranged in a plurality of scattering planes tilted relative tothe first face of the scattering volume; wherein the image outputcomprises a set of image slices; each image slice of the setcorresponding to a unique spatial partition of a three-dimensional imagedataset; each image slice of the set projected onto a plane of theplurality of scattering planes.
 6. The volumetric display of claim 5,further comprising an anamorphic lens optically located between thelight source and the scattering volume; wherein the anamorphic lenstransforms the two-dimensional image output generated by the lightsource such that an aspect ratio of the image output is modified, by amodification factor, from an original aspect ratio to a transformedaspect ratio.
 7. The volumetric display of claim 6, wherein thescattering planes of the scattering volume display image slices of theimage output such that the image slice displayed by each scatteringplane is restored to the original aspect ratio.
 8. The volumetricdisplay of claim 7, wherein the three-dimensional array of scatteringelements has a height equal to a scattering plane width multiplied bythe square root of the difference of one over the modification factorsquared and one.
 9. The volumetric display of claim 7, wherein each ofthe plurality of scattering planes has a same uniform width; wherein thethree-dimensional array of scattering elements has a height equal to animage output width, divided by a count of the plurality of scatteringplanes, multiplied by the square root of the difference of one and themodification factor squared.
 10. The volumetric display of claim 7,wherein the anamorphic lens is a three-element cylindrical anamorphiclens.
 11. The volumetric display of claim 5, further comprising adihedral corner reflective array (DCRA) coupled to a surface of thescattering volume; wherein the DCRA creates a real image of athree-dimensional image displayed within the scattering volume.
 12. Thevolumetric display of claim 11, wherein the DCRA comprises atwo-dimensional array of dihedral corner reflecting elements positionedsuch that light exiting the scattering volume is able to reflect twiceinside the dihedral corner reflecting elements, resulting in incidentlight traveling along a path plane-symmetric to an incident path. 13.The volumetric display of claim 12, wherein the dihedral cornerreflecting elements comprise rectangular through-holes etched in ametallic film.
 14. The volumetric display of claim 11, wherein the realimage and the three-dimensional image have identical dimensions.
 15. Thevolumetric display of claim 14, wherein the scattering elements arehighly directional and scatter a majority of incident light towardreflectors of the DCRA.
 16. The volumetric display of claim 5, whereinthe volumetric display has a one-to-one voxel to pixel relationship. 17.The volumetric display of claim 5, wherein the volumetric display has aone-to-many voxel to pixel relationship.
 18. The volumetric display ofclaim 5, wherein the volumetric display has a many-to-one voxel to pixelrelationship.
 19. The volumetric display of claim 5, further comprisingan opaque shield that restricts a viewing angle of the scatteringvolume.
 20. The volumetric display of claim 5, further comprising afiltering film applied to a surface of the scattering volume thatrestricts a viewing angle of the scattering volume.